PROBLEM TO BE SOLVED: To solve the problems wherein, in an electromagnetic actuator provided with an excitation coil instead of an electromagnet, a large power consumption is required in an excitation part regardless of the intensity of a required test force, and when malfunction in which a heavy current flows in a movable coil occurs, an excessive test force is suddenly generated, to thereby generate a dangerous state.
SOLUTION: A magnetic flux density generated by the excitation coil included in the electromagnetic actuator 12 is switched according to an operation mode, namely, the state of a material test. In a mounting stage of a test piece TP, a thrust enough to grip the test piece TP by grippers 38, 40 by moving vertically a piston rod 13A is generated from the electromagnetic actuator 12. In a test execution stage, the magnetic flux density is set so that a rated test force is acquired. After the material test is finished, the magnetic flux density is set so that a magnetic flux density equivalent to that in a preparation stage of the material test is acquired.
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